1. Field of the Invention
The present invention relates to an interposer package and a method for fabricating the same, and in particular, to a molded interposer package and a method for fabricating the same.
2. Description of the Related Art
An interposer is an electrical interface routing between sockets or connecting one socket to another socket. The purpose of an interposer is to widen the pitch of a connection from a bump pitch of a chip or to reroute a connection. The conventional interposer formation, starts with a resin-based core substrate formed by laminated bismaleimide triazine (BT). Next, a through via etching process, insulation oxidation process, metal filling process, multilayer wiring process, solder mask process, micro bumping process, chip mounting process and mold cap process are performed in sequence. It is noted that the conventional core substrate and the through vias are composite structures. The conventional multilayer wiring process and the solder mask process are required to fabricate interconnect structures and solder masks on both sides of the core substrate. The conventional mold cap process is needed for package rigidity. Therefore, the conventional interposer has a high fabrication cost due to the aforementioned complicated process steps. Also, the conventional resin-based core substrate only can be fabricated in a small size because of its poor mechanical strength. The aforementioned disadvantages limit the development of interposer technology. Further, the conventional interposer suffers various design challenges. For example, it is difficult for the conventional interposer to provide a suitable power delivery network for both the core substrate and I/Os, including options for wider power traces, dedicated power planes, dedicated power islands and on-board decoupling capacitors. Also, it is difficult for the conventional interposer to provide configuration options for side-by-side, package-on-package and side-by-POP DRAM memory bus, increase thermal conductivity through the substrate and solder balls, provide of an option for a clip-on heat spreader, maintain current customer printed circuit board (PCB) circuit density limitations, and provide configuration options for multi-die and hybrid wire bonding.
Thus, a novel interposer package structure is desirable.